KLK3 and prostate cancer: Prostate-specific antigen (PSA) was 1.810 ng/ml; urinary flow rate was 5.9 ml/s, urinary system ultrasound showed a prostate size of ~4.5 × 4.0 × 3.6 cm, and prostate MRI indicated unclear boundaries between the central gland and peripheral zone, with multiple patchy low signals on T2-weighted imaging (T2WI) and fat-suppressed imaging, and high signals on diffusion-weighted imaging (DWI) with reduced apparent diffusion coefficient (ADC) values, suggesting prostate cancer (Fig. 1A–D).